The other day we replaced the internal fuel feed and return lines, and now the truck is running like crap! The SES was on and flashing. I thought the flashing meant that it was throwing different codes. Unfortunately, now the only code it's reading is 0300 (why do they even HAVE that code??). Any ideas?
The truck was running pretty well before the fuel lines were replaced, except it would cut out sometimes when it was warm. Normally engine runs at around 160 degrees or so, but if the outside air temp was over 88 degrees and the truck had been running for a while, (like on the freeway for at least 30 minutes) the temp guage would creep up to about 220 and the engine would quit. When you tried to re-start the fuel pump would howl and it wouldn't start. But after sitting for a while it would start again. Also during this time the SES light would come on for a while, and then go out, just under normal city driving conditions. But as far as running, the engine was running great-smooth, quiet, getting normal gas mileage. About 6 months before this started happening, we had replaced the internal fuel feed line which was cracked. However, the replacement line we used was "made" for us in a friend's shop, and it was not exactly the right size, it was a little too long but it worked. Then we started having the problem with the truck cutting out. Husband figured since the line was too long it was starting to crimp when it got warm. Thus, engine dies and fuel pump howls. So, we got a nut kit from NAPA, replaced the internal lines again, and now the engine is running totally crappy misfiring all over the place. They've taken the upper manifold off twice and re-checked everything, and all seems to be good. Any ideas what might be going on???

 

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